STATE AND PHASE TRANSITIONS AND QUALITY CHANGES IN FROZEN  STARCH-RICH FOODS

Pavitra   Krishna Kumar

The frozen food industry is growing at a tremendous rate, owing to changes in lifestyle and increased purchasing capacity among consumers. The science and technology of food freezing has advanced very well- ice crystal visualization and control of crystal growth, assisted freezing technologies and improved freezing processes have led to frozen foods with better stability and properties during their shelf life. However, there is loss in quality of frozen food due to unavoidable temperature fluctuations during handling, storage and transportation. Based on their characteristic thermal transition temperatures, food matrices undergo changes in state and phase during temperature fluctuation from the frozen state, leading to ice recrystallization: there is repeated melting and refreezing of ice crystals in frozen food, leading to change in their number, size, shape and location within the food. As a result, there is loss in the physical, chemical and microbial quality of the food. In this study, frozen starch-rich foods, namely potato and rice have been chosen. The thermal transition parameters of these foods have been determined, and phase and state transitions have been induced by temperature fluctuations. The resulting ice recrystallization has been examined microscopically. The accompanying changes in hardness of potato and in starch retrogradation enthalpy of rice have been measured. The results indicate that the extent of ice recrystallization relates well with state/phase transitions in potato and rice. However, there is no impact on hardness in potato as a result of temperature fluctuation. Also, there is reduction in the starch retrogradation enthalpy of rice as a result of temperature fluctuation during frozen storage. Hence, starch-rich foods are less sensitive to temperature fluctuations compared to protein (e.g. fish) and sugar-rich (e.g. mango) foods. The study will lead to an optimized frozen storage management e.g. during the commercial handling of a wide variety of frozen foods, foods such as ice cream, fish etc. that are more susceptible to the implications of temperature fluctuation could be placed closer to evaporator, where there is less temperature fluctuation, while foods such as French fries and sushi etc. could be placed closer to doors of the cold room, where there is more temperature fluctuation, due to repeated opening and closing of the door.

STATE AND PHASE TRANSITIONS AND QUALITY CHANGES IN FROZEN STARCH-RICH FOODS

Files and links (1)

Abstract

Metrics

Details